1. Field of the Invention
The present invention relates to a novel chromatic-color metal flake pigment and a method for the preparation thereof as well as a colored composition, such as coating compositions, inks, cosmetic preparations and molding compounds of plastic resins, compounded with such a chromatic-color pigment. More particularly, the invention relates to a chromatic-color metal flake pigment of which each metal flake is provided on the surface with a coating layer of titanium oxide and an efficient method for the preparation of such a pigment, as well as a colored composition of high aesthetic value compounded with such a pigment such as coating compositions or paints, ink compositions, cosmetic preparations, molding compounds of plastic resins and the like.
2. Background Information
It is known in the art of coating compositions, inks, cosmetic preparations, molding compounds of plastic resins and the like to compound the compositions with metal flake pigments of metal selected from the group consisting of aluminum, bronze, stainless steel, tin, and iron, organic pigments, inorganic pigments, dyes, or pearlescent pigments prepared by forming a coating layer of titanium dioxide on the surface of mica flakes as a material capable of giving high aesthetic value to the composition. These pigments and dyes are used either singly or as a combination of two kinds or more in accordance with the need to obtain a specific highly aesthetic effect of coloring.
Along with the trend in recent years to desire to have various products capable of giving an impression of a personalized high-class product in appearance, consumers' demand is directed toward a novel aesthetic value which can never be obtained with the above mentioned coloring or colored materials. For example, a highly aesthetic coloring effect capable of giving an impression of high-class goods with a silky appearance is desired of which the impression of color received by a viewer is subject to delicate change depending on the angle of incident light and the view angle with reduced glaringness inherent in conventional metal flake pigments.
Several proposals have been hitherto made for novel coloring materials to meet the above mentioned desire. For example, Japanese Patent Kokai 59-126468 and 61-225264 propose a chromatic-color pearlescent pigment of which mica flakes are provided with successive two coating layers of, one, a lower oxide of titanium and, the other, titanium dioxide and a coating composition compounded with such a chromatic-color pearlescent pigment. Japanese Patent Kokai 51-150532 proposes a colored aluminum pigment prepared by providing flakes of metallic aluminum with a coating layer of a hydroxide of metal such as iron and the like.
Though having a higher hiding power than conventional pearlescent pigments, the above mentioned mica-based chromatic pearlescent pigment has a problem in the relatively low weatherability so that this pigment cannot be used in applications in which long-term weatherability is essential as in the field of coating compositions. The colored aluminum pigment above mentioned is also defective in respect of the weatherability and does not always give a quite satisfactory result when it is used as a coloring agent of a coating composition of which long-term weatherability is essential.